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Discussion Starter #1
I've been having driveability issues with my 2006 Mazda 6 V6 manual since the day I bought it back in September, but I also had a fuel pump issue and an intermittent misfire to take care of first before I tracked this one down (I thought it was related to those issues, but turns out it's its own thing). Based on the behavior, I'm thinking throttle body, because there's a significant delay between what my foot does and the engine's response. For example, it takes a good 3 seconds after a stomp of the pedal before the engine will make any power, and this is at any RPM. I also have been having an issue where if I'm more than say 50% throttle, the engine will rev between shifts, and I've taken great care to make sure my foot is off the accelerator all the way before the clutch goes in. I'm no newb at driving manual either. I've driven over a dozen manual vehicles probably about a half million miles all told, so I'm confident it's not my technique.

So today I took off the intake tube and with key on engine off, I ran the throttle pedal down a few times and recorded video of the throttle plate movement with my cell phone camera, and the throttle plate moves dog slow. Even before I started hitting the throttle pedal, I noticed a weird whining/chirping noise coming from the throttle body too, almost like an old school computer processor would make. I did a second video of me just mashing the pedal to the floor and holding it down. It showed a full 5 seconds for the throttle plate to go from full close to full open, and I maybe took a tenth of a second to push it down inside the car. It also seemed to be having a hard time holding the throttle plate open once it was all the way there, wavering a little bit.

Now my question is this, before I go spending hundreds on a throttle body or tracking one down in the junk yard, is there any chance that this is normal behavior? Like, did Mazda tune it to operate super slow for emissions purposes? I'm almost certain it's a bad throttle body, but just wanted to confirm I'm not seeing something related to the way drive by wire systems work. If anyone has some expertise in this area, I would very much appreciate any info you might have.
 

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This engine is slow as molasses in the lower rpms for sure, but a "delay" is weird. Just out of curiosity, does it behave the same with traction control off?
 

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Discussion Starter #4
This engine is slow as molasses in the lower rpms for sure, but a "delay" is weird. Just out of curiosity, does it behave the same with traction control off?
Same same with the traction control off. I wouldn't call it slow, I'd call it complete lack of power. I've noticed the kick you get at about 4k once it finally starts going, I'm assuming from the variable cam, but it's more like: nothing, nothing, nothing, okay we're making a little bit of power and RPM's are climbing, then 4k hits and hold on to the wheel we're getting torque steer. I've also tried it above that RPM on the highway, cruise steady at like 4500 and then mash the throttle, and there is still a delay from when I hit the throttle to when it makes power, although it's a bit quicker up there. My old Saturn with the 1.9L 4-cylinder had more power and torque off idle than this thing does at any street-friendly launch RPM, and that was the weak point on that little 4 banger. Sometimes when I blip to raise the RPM at a stop light to avoid stalling it does nothing before I lift the clutch. Very frustrating to drive it like this. Definitely something wrong here. Did you happen to watch the video? That's not normal for a throttle body to take that long opening is it?
 

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Discussion Starter #6
It closes fast, but opens slow, its no the motor, so id clean the fuck outta it.
Thanks for the reply. I'm confused though. Are you saying that this is normal behavior or that it's not working correctly and cleaning it might fix the problem? Also, by motor, do you mean the electric motor inside the throttle body assembly that turns the throttle plate or the car's engine?
 

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Discussion Starter #8
Here is my 2004 6s throttle body opening for comparison.
Maybe try grounding the TB to the battery negative or possibly disconnecting the battery and resetting the PCM?
Thank you very much for that DrFeelGood. Now I'm certain that there's a malfunction. I actually just did the PCM reset after my first post on this thread. Car seemed to drive a lot better after letting it idle up to temp at first but now it's doing weird crap again. I even pulled the throttle body off and checked out the gears. Everything inside looked fine. No signs of corrosion or any damage to the gear teeth. All the electrical contacts both inside and out look fine. I did the ground when I first got the car, you can see it in the video on the upper left bolt. I'm thinking new throttle body is my next move here.

It kind of amazes me that it doesn't throw any codes when there's such a discrepancy between the throttle pedal position and the position of the throttle plate. I think I might poke around in Forscan and see if I can look at the two values and see if the computer even senses what I'm seeing. It might help me narrow down the problem.
 

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Thank you very much for that DrFeelGood. Now I'm certain that there's a malfunction. I actually just did the PCM reset after my first post on this thread. Car seemed to drive a lot better after letting it idle up to temp at first but now it's doing weird crap again. I even pulled the throttle body off and checked out the gears. Everything inside looked fine. No signs of corrosion or any damage to the gear teeth. All the electrical contacts both inside and out look fine. I did the ground when I first got the car, you can see it in the video on the upper left bolt. I'm thinking new throttle body is my next move here.
You are welcome. I am glad it helped.
If you can't easily fix it and don't score one from a salvage then this site may be of help.
Good luck.
 

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Discussion Starter #10
It closes fast, but opens slow, its no the motor, so id clean the fuck outta it.
I thought about it more, and I think I know what you're saying. The fact that it closes fast is because the throttle plate is spring loaded. Doesn't matter if the electric motor works well or not, as soon as that gear doesn't have any force on it, the spring will pop it back to closed.
 

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Okay, so I did a little bit of research last night and found some info on one of the RX8 forums. Somebody posted a procedure for a throttle body relearn for those cars. With the car cold, you turn the key on but don't start, push the brake pedal 20 times or until you see the oil pressure gauge sweep. In my case I saw the check engine light start flashing a few pumps before I got to 20. Anyway, then you shut the key off, wait a few seconds, then start the car and let idle up to temp. For the first test drive after this procedure it was working great except that while coasting in neutral or with the clutch in, it would idle down to 500 RPM. It was making good power at sub 4000 RPM and I was just taking it easy so the fuel trims for normal driving could be properly learned by the computer. After about 20 miles of this, I gave it one rip above 4000 RPM for a couple of gears, and then I started getting my hesitation again. Not nearly as bad as before, but still a delay between when I depress the throttle and it starts making power. Shutting the car off and restarting/driving fixed the 500 RPM coast idle thing, but it was still driving weird.
I slept on it last night and checked the throttle body with my camera again. The super slow throttle opening is completely gone now. I hooked up Forscan and looked at all the throttle position sensors and the throttle pedal and everything there seems to be working as it should. Something to note, the throttle is being told by the computer to open a bit slower. I'd say third second between full open and full close even though I'm doing instant WOT with the pedal. Both the "throttle position actual" and "throttle position commanded" readouts changed proportional to each other, so I know the throttle body is doing what it's told by the computer now. I consider this particular issue fixed unless I start seeing that 3 second delay again.
Now that the throttle body is working as it should, I need to figure out why the computer is locking me out for a moment when I stomp the go pedal. I haven't ruled out that the factory tune is doing this for emissions or fuel consumption reasons. Oh, also, just for curiosity's-sake, I added the cam timing to the readout when i was driving, and I found that the difference between commanded and actual was close to 0 most of the time, so I'm ruling out a cam timing issue. Now I'm thinking knock sensor or maybe EGR? If anyone's got suggestions of which sensors to look at next, I'm all ears.
 

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I thought about it more, and I think I know what you're saying. The fact that it closes fast is because the throttle plate is spring loaded. Doesn't matter if the electric motor works well or not, as soon as that gear doesn't have any force on it, the spring will pop it back to closed.
It snaps closed pretty quick so I would think the linkage is mostly clean/clear. My thoughts are with a motor that is dying or some type of signal loss where the motor is not getting the signal/current to open properly, (either within the TB or from the accelerator pedal)
Pico Tech has a how to for testing the accelerator pedal although you sound like you don't need it. :geek:


Edit: this was posted while the previous post was being added.
 

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This is great info. My car has always been sluggish at low rpm's and the throttle hangs when high rpm shifting. I'll try this procedure and see what it does.

Okay, so I did a little bit of research last night and found some info on one of the RX8 forums. Somebody posted a procedure for a throttle body relearn for those cars. With the car cold, you turn the key on but don't start, push the brake pedal 20 times or until you see the oil pressure gauge sweep. In my case I saw the check engine light start flashing a few pumps before I got to 20. Anyway, then you shut the key off, wait a few seconds, then start the car and let idle up to temp. For the first test drive after this procedure it was working great except that while coasting in neutral or with the clutch in, it would idle down to 500 RPM. It was making good power at sub 4000 RPM and I was just taking it easy so the fuel trims for normal driving could be properly learned by the computer. After about 20 miles of this, I gave it one rip above 4000 RPM for a couple of gears, and then I started getting my hesitation again. Not nearly as bad as before, but still a delay between when I depress the throttle and it starts making power. Shutting the car off and restarting/driving fixed the 500 RPM coast idle thing, but it was still driving weird.
I slept on it last night and checked the throttle body with my camera again. The super slow throttle opening is completely gone now. I hooked up Forscan and looked at all the throttle position sensors and the throttle pedal and everything there seems to be working as it should. Something to note, the throttle is being told by the computer to open a bit slower. I'd say third second between full open and full close even though I'm doing instant WOT with the pedal. Both the "throttle position actual" and "throttle position commanded" readouts changed proportional to each other, so I know the throttle body is doing what it's told by the computer now. I consider this particular issue fixed unless I start seeing that 3 second delay again.
Now that the throttle body is working as it should, I need to figure out why the computer is locking me out for a moment when I stomp the go pedal. I haven't ruled out that the factory tune is doing this for emissions or fuel consumption reasons. Oh, also, just for curiosity's-sake, I added the cam timing to the readout when i was driving, and I found that the difference between commanded and actual was close to 0 most of the time, so I'm ruling out a cam timing issue. Now I'm thinking knock sensor or maybe EGR? If anyone's got suggestions of which sensors to look at next, I'm all ears.
 

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Discussion Starter #14
Just a heads up again @banzairx7, this didn't fix all my woes, it just stopped the condition where I had an extreme delay between throttle application and power. Now it's a short delay lol (nothing... -> power; as opposed to nothing... nothing... nothing... -> hold on for dear life!). I'm still getting that weird hesitation at high RPM unless I power shift it and don't really let the RPM's drop between shifts, which I don't like to do because I'm worried something's going to break.
 

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I've been having driveability issues with my 2006 Mazda 6 V6 manual since the day I bought it back in September, but I also had a fuel pump issue and an intermittent misfire to take care of first before I tracked this one down (I thought it was related to those issues, but turns out it's its own thing). Based on the behavior, I'm thinking throttle body, because there's a significant delay between what my foot does and the engine's response. For example, it takes a good 3 seconds after a stomp of the pedal before the engine will make any power, and this is at any RPM. I also have been having an issue where if I'm more than say 50% throttle, the engine will rev between shifts, and I've taken great care to make sure my foot is off the accelerator all the way before the clutch goes in. I'm no newb at driving manual either. I've driven over a dozen manual vehicles probably about a half million miles all told, so I'm confident it's not my technique.

So today I took off the intake tube and with key on engine off, I ran the throttle pedal down a few times and recorded video of the throttle plate movement with my cell phone camera, and the throttle plate moves dog slow. Even before I started hitting the throttle pedal, I noticed a weird whining/chirping noise coming from the throttle body too, almost like an old school computer processor would make. I did a second video of me just mashing the pedal to the floor and holding it down. It showed a full 5 seconds for the throttle plate to go from full close to full open, and I maybe took a tenth of a second to push it down inside the car. It also seemed to be having a hard time holding the throttle plate open once it was all the way there, wavering a little bit.

Now my question is this, before I go spending hundreds on a throttle body or tracking one down in the junk yard, is there any chance that this is normal behavior? Like, did Mazda tune it to operate super slow for emissions purposes? I'm almost certain it's a bad throttle body, but just wanted to confirm I'm not seeing something related to the way drive by wire systems work. If anyone has some expertise in this area, I would very much appreciate any info you might have.
I've been having driveability issues with my 2006 Mazda 6 V6 manual since the day I bought it back in September, but I also had a fuel pump issue and an intermittent misfire to take care of first before I tracked this one down (I thought it was related to those issues, but turns out it's its own thing). Based on the behavior, I'm thinking throttle body, because there's a significant delay between what my foot does and the engine's response. For example, it takes a good 3 seconds after a stomp of the pedal before the engine will make any power, and this is at any RPM. I also have been having an issue where if I'm more than say 50% throttle, the engine will rev between shifts, and I've taken great care to make sure my foot is off the accelerator all the way before the clutch goes in. I'm no newb at driving manual either. I've driven over a dozen manual vehicles probably about a half million miles all told, so I'm confident it's not my technique.

So today I took off the intake tube and with key on engine off, I ran the throttle pedal down a few times and recorded video of the throttle plate movement with my cell phone camera, and the throttle plate moves dog slow. Even before I started hitting the throttle pedal, I noticed a weird whining/chirping noise coming from the throttle body too, almost like an old school computer processor would make. I did a second video of me just mashing the pedal to the floor and holding it down. It showed a full 5 seconds for the throttle plate to go from full close to full open, and I maybe took a tenth of a second to push it down inside the car. It also seemed to be having a hard time holding the throttle plate open once it was all the way there, wavering a little bit.

Now my question is this, before I go spending hundreds on a throttle body or tracking one down in the junk yard, is there any chance that this is normal behavior? Like, did Mazda tune it to operate super slow for emissions purposes? I'm almost certain it's a bad throttle body, but just wanted to confirm I'm not seeing something related to the way drive by wire systems work. If anyone has some expertise in this area, I would very much appreciate any info you might have.
 

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Another problem you may be having is the MAF sensor you can try to clean it or just go to rockauto they always have a very good price.
 

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Its the ecu, no it cant be. Its the ecu, no those things are bullet proof. Its the ecu, must be the sensors.
Its the ecu, nope there has to be a better diagnosis. Thanks for all the info, we usually have to milk it out of people.
I'm confident you will find the answer, please not be the ecu.
 

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THIS is exactly what I have been looking for. I have a couple posts out there where I have been describing this kind of sluggishness.
Subscribed!!
 

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Discussion Starter #19
Here's another update. Sorry for the wait but I don't drive the car much and had to wait until I put some miles on it to see if any more issues popped up. Original problem has returned except now it's intermittent. On startup and when it's cold, it runs and drives perfect with no detectable delay in throttle response. When the engine gets hot, I get varying degrees of delay in the throttle. Sometimes the 3-5 second delay, sometimes just a momentary hesitation. I hooked my laptop back up with Forscan to take a look at the behaviors of all the sensors again. Throttle pedal % is always instantly where my foot is. When I went and looked at throttle position (at the throttle body), vs what the computer is telling the throttle to do (desired), they seem to consistently match. This means the throttle body and the throttle pedal are decidedly not malfunctioning. The computer is receiving the message loud and clear and then just doing its own thing. There's a huge delay between my throttle pedal % number and what the computer says the throttle position should be. The % of desired throttle climbs very slowly until 100%, then I finally get a surge of power when it hits that 100% number. I tell the computer I want power now, and the computer answers back "you need to wait until I get around to it."

Other than a malfunction of the computer itself, the only explanation I can come up with is emissions. Here's my theory: On an old carbureted engine, when you push the throttle and open the butterflies, the accelerator pump dumps gobs of fuel in there to enrich the fuel mixture. This obviously isn't great for emissions because it sends unburned fuel out the exhaust. Early fuel-injected cars have the same function, they just do it at the injectors when the throttle plate is opened by the cable connected to your foot pedal. While not quite as bad as with a carburetor, still not great for emissions. On drive by wire systems, maybe they just bypass this tuning problem by having delayed throttle opening. On a rev-happy engine like this, the effect is pronounced.

Honestly I'm thinking about getting rid of the car at this point because of the way it drives, especially if this is what it's designed to do. I'm leaning towards this conclusion since I formerly had a 2012 Fusion (also a 3.0 Duratec) which did the exact same thing. It makes me sad because I like everything else about this platform. The throttle delay just takes the joy out of driving manual for me. It's more fun to drive my pickup because it just goes when I hit the gas.
 
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